The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
A typical manual transmission includes a plurality of shafts, gears, shift mechanisms, synchronizers or other torque-transmitting mechanisms that cooperate to provide a plurality of forward and reverse gear or speed ratios. The transmission input shaft is selectively connected to an engine output shaft and includes a number of gears that are selectively connectable to the input shaft using, for example, synchronizers. The gears of the input shaft mesh with corresponding gears that are selectively connectable to an output shaft. To achieve a particular forward gear ratio between the transmission input and output shafts a shift mechanism, such as a manual shifter, controls the engagement of the synchronizers with the desired gears. To shift from the neutral gear to a reverse gear ratio, a reverse gear is used to slide between an input shaft gear and an output shaft gear to reverse the rotational direction of the output shaft.
The reverse gear selectively meshes with the input shaft reverse gear. When meshed, both the input shaft reverse gear and the reverse gear rotate together at about the same speed. The reverse gear then engages with the output shaft gear to transfer torque from the input shaft to the output shaft. The output shaft is usually stationary or rotating in the opposite direction from the reverse gear. If the output shaft is stationary or rotating in the opposite direction, the meshing of the reverse gear with the output gear can cause an impact or gear clash that creates a loud scratching and grinding noise. This noise can be especially objectionable if the reverse gear is rotating at a high speed relative to the output shaft. Gear clash is detrimental to the long term durability of the transmission and can be the source of costly customer repair bills. A reverse gear synchronizer system can be employed to stop the reverse gear from rotating when engaging with the output shaft, however this reverse gear synchronizer system can be costly to implement.
Accordingly, there is room in the art for a transmission that includes a cost-effective mechanism to reduce gear clash by reducing the input shaft and reverse gear rotational speed when the driver is shifting into a reverse gear ratio.